The single most important thing that any smoker can do to improve their current and future health, is to stop smoking.

When discussing options for quitting, cutting down or temporary abstinence it is our responsibility to inform you that using an e-cigarette is far safer than smoking and that an e-cigarette:

Effectiveness
Nicotine (delivered quickly to the brain via inhaled smoke) is the main reason that smoking cigarettes is so addictive. Nicotine is the reason people continue to smoke despite suffering from tobacco-related diseases or wanting to quit – it is also the reason people relapse back to smoking.

For regular smokers, the absence or reduction of nicotine after only an hour or so results in withdrawal symptoms. These are alleviated when a cigarette is smoked and nicotine levels rise. Smokers wishing to quit, manage temporary abstinence or reduce harm from their cigarette smoking all benefit from nicotine doses from vaping that match or get close to the nicotine levels achieved by smoking cigarettes.

Nicotine delivery from e-cigarettes is affected by the:

Device technology
Nicotine delivery from e-cigarettes has generally increased with successive generations of the technology. See next section: Device types.

The early, first generation (cigalike) e-cigarettes delivered little or no nicotine. A 2010 study of a cigalike reported that they produced a maximum blood nicotine concentration of 1.3ng/ml. Far lower than the 13.4ng/ml achieved with smoking a cigarette and less than even the Nicorette® nicotine inhalator (2.1ng/ml).

As e-cigarette technology has improved, so also has nicotine delivery. This has produced blood nicotine levels that are similar to those obtained from oral NRT products, but achieved significantly faster. One study showed that peak blood nicotine levels were reached within five minutes after starting to use the device.

E-liquid
Using e-liquids with higher nicotine concentration increases nicotine delivery and propylene glycol in e-liquid may also aid nicotine delivery. Propylene glycol has a lower boiling point (187.6 °C) than glycerine (290 °C), which may account for a better delivery of nicotine in solutions that contain it.

Nicotine concentration in e-liquid is normally represented on the labels as mg/ml (sometimes shortened to just mg) or %.

So 12mg/ml of nicotine in an e-liquid could be expressed as 12mg nicotine or 1.2% – they mean the same thing.

The maximum nicotine concentration permitted in the UK is 20mg/ml (2%). Typically, nicotine content in e-liquid comes as 0mg/ml (0%), 3mg/ml (0.3%), 6mg/ml (0.6%), 12mg/ml (1.2%), and 18mg/ml (1.8%).

Puffing technique
Higher peak blood nicotine concentrations have been found in experienced e-cigarette users (e.g. 13–14ng/ml) after an hour of ad lib (as they wished) use. This is similar to the levels seen after smoking a cigarette and e-cigarette users can have similar levels of cotinine, a metabolite of nicotine, in saliva as regular smokers.

A UK study found that among naive users, five minutes ad lib use of an e-cigarette containing 24mg/ml of nicotine produced a peak plasma concentration of 4.6ng/ml within five minutes; after four weeks of practice these users achieved levels of 5.7ng/ml.

Practice in the technique of using e-cigarettes is therefore clearly important, but it is likely to be subconscious ‘practice’ involving simply using and getting better at using devices.